.showDiv{
    position: absolute;
    left: 0px;
    top: 0px;
    background-color: rgba(0,255,255,0.4);
    width: 500px;
    height: 500px;
    visibility: hidden;
    display: flex;
    justify-content: center;
    align-items: center;
}
.contentDiv{
    width: 600px;
    height: 500px;
    padding: 20px;
    background-color: yellow;
}

#headDiv{
    width: 1200px;
    height: 80px;
    background-color: rgba(255,0,0,0.4);
    font-size: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
}